Electric-arc lamp.



Patented Apr. I5, I902.

H. BBEMER.

ELECTRIC ARC LAMP. (Application filed Sept. 26, 1900.

(N0 Model.)

.1; vmfor' 74 [1 2 'inawraw THE "cams PETERS co. mom-Limo. wnsmum'ou. u.c.

UNITED STATES PATENT OFFICE;

HUGO BREMER, OF NEHEIM, GERMANY.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of Letters Patent No. 697,439, dated April15, 1902.

Applicationfiled SeptemberZB, 1900. Serial No. 31,193. (No model.)

To all whom it may concern.-

. Be it known that I, HUGO BREMER, a subject of the Emperor ofGermany,residing at Neheim-on-the-Ruhr,in the Province of Westphalia, Germany,have invented a new and useful Improvement in Electric-Arc Lamps, ofwhich the following is a specification.

In electric-arc lamps many devices have been proposed to prolong thelife of the electrodes, which, as is well known, is shortened by theair-currents flowing around the carbons. The most effective structurehas been found in arranging a chamber or cylindrical.

body around the pencil ends, which prevents access of air to the saidends and in such a manner secures a longer life of the carbons. The useof such a chamber with ordinary carbon is objectionable owing to thefact that it decreases the light emission, and while it raises thetemperature of the luminous are no means are provided by which thisincrease of temperature is utilized. Even the arc will be less luminousthe more the temperature around it rises.

A great improvement has been realized in arc-lamps arranged as above byproviding them with carbon pencils containing an addition of metallicsalts or such substances as have a higher temperature of combustion orVolatilization than carbon itself. Such carbon pencils will in any casecause a highlyluminous arc; but the temperature of incandescence and thepower of emission of light possessed by the, substances will beintensified in proportion to the heat generated by the combustion ofcarbon. Seeing now that such reflectors materially increase thetemperature around the burning carbon points, it is just in the case ofarc-lamps of this kind that a materially-improved effect is obtained bythe application of the carbon pencils just referred to. Consequentlywhile with ordinary carbon pencils the reflectorswill cause adisadvantage as regards the yield of light, on account of the highertemperature or re duced luminosity of the arc, with the use of theaforesaid special carbon pencils the Very cause thereof is utilized forrealizing an improvement.

In arc-lamps described as my inventionthat is, having carbon pencilscontaining an addition of metallic salts-said pencils are placeddownwardly, pointing parallel or converging, and inclosed at theirpoints by a chamber,abovedescribed. Thiscombination presents the greatadvantage that the arc can be projected downward in a crescent-shaped orfan-like form, its color being rendered more uniform and homogeneousowing to the circumstance that the light, so to speak, is seething inmetallic vapors. At the same time the temperature around the luminouspoints is increased, and consequently an extraordinarily intensifiedluminous effect is produced in the case of carbon pencils impregnatedwith metallic salt which are placed with their points directed downward.The crescent-shaped or fan-like formation of the arc, which of courseentails an increase of its area, and consequently an increased luminouseffect, can be obtained with ease and certainty by the arrangement of anelectromagnet energized by the current of the lamp and the magneticfield of which acts on the arc, either attracting or repelling it andprojecting it outward, so as to impart to it the above-mentioned shape.On the other hand, in the case of arc-lamps in which a magnetic field orsolenoid is arranged for the purpose of regulating the resistance in thearc itself in accordance with the requirements of steady burning or forthe purpose of deflecting it in a certain direction it is particularlyadvantageous to use carbon pencils containing an addition of metallicsalts or such substances as will yield a luminous arc, because in thiscase the deflection of the are involved by regulating or directing thearc causes an enlargement of the area of the arc which if the arc itselfis luminous must at the same time entail an increased luminous effect.

The arrangement described above of carbon pencils impregnated withmetallic salts may also be applied without further modification foralternating-current arc -lamps. It is a well-known fact that a greatdisadvantage of these lamps is that nearly onehalf of the light emittedby the incandescent carbon points is projected upward and can only bethrown downward with a certain loss by means of a reflector. This ismainly due to the fact that ninety per cent. of the emitted lightemanates from the crater-surfaces, and as the lower one of these emitsjust as much light as the upper one the above-mentioned effect results.

A modification of the direction in which the light is emitted inalternating-current lamps can be obtained by adding substances to thecarbon pencils which will render the arc luminous, thus givinga lesspreponderant pro portion to the light emitted by the crater-sur faces. Again in the radiation of light is more especially realized in thehorizontal direction, which is of particular value for some purposes,while, on the other hand, the radiation of light in an upward directionand with it the coefficient of loss is reduced. Experiments have alsoshown that itis thereby rendered possible to work alternating-currentlamps with a higher voltage than is practicable in the case of ordinaryelectrodes. \Vhen applying a higher voltage and, accordingly, a greaterdistance between the carbon points, correspondingly more light isobtained, the are being luminous, while if ordinary carbon pencils areused no increase of light is obtained notwithstanding the increaseddistance between the carbon points, as thearc is not luminous.

On the accompanying drawings, Figure 1 shows aconstructionhavinganair-case. Fig. 2 is a similar construction in connection with amagnet. Fig. 3 is a horizontal section of Fig. 2. Fig. iis a devicehaving a reflectorplate. Fig. 5 is a device without case.

Referring to the drawings, the referenceletters a d, Fig. 1, designate apair of carbons being placed downwardly pointing and parallel to eachother. As described above, these pencils contain a highadditionforinstance, twenty to seventy per cent-of metallic salts, ascalcium fluor and the like, which renders the voltaic are very luminousand elastic, the carbons being fitted in tubes 1) or other suitableholders projecting through a plate 0, and their points are surrounded bya hollow casing c. This casing, which may be of any form, forms achamber around the points and prevents to a certain degree admission ofair to the voltaic are, so that the latter, which consists of theburning metal particles, is kept in its high illuminating state. Nearlythe same effect may be obtained by the construction shown in Fig. 4,where a plate 0 of any form or an equivalent forms an agent by which insome way air is prevented from rising or coming from above,

so that again the arc is kept highly incandcscent.

Figs. 2 and 3 show a device constructed as Fig. 1 in connection with amagnetic field. For this purpose a magnet d or a solenoid may bearranged in the casing, as shown, which produces its lines of force insuch a manner that thearc becomes considerably enlarged, which may beeasily done according to its elasticity.

Fig. 5 showsa construction in which the easing is dispensed with andwhich consists only of the downwardly-pointing carbon pencils and amagnet. 'It has been found that the are when being submitted to thelines of force of the magnetic field was also greatly enlarged, assumingthe shape of a knife-blade, the matter contained in the arc andconsisting of a large number of exploding particles being thus spreadasunder and equally exposed to the influence of air, so that the colorgets more homogeneous, and also the calm of the arc is considerablyincreased.

hat I claim, and desire to secure by Letters Patent, is

1. In an electric-arc lamp, search-light, &c., the combination of a pairof downwardlypointed parallel or converging carbon pencils containing ahigh percentage of metallic salts and a chamber surrounding the carbonends for the purpose described and set forth.

2. In an electric-arclamp, search-light, &e., the combination of a pairof downwardlypointed parallel or converging carbons containing a highpercentage of metallic salts a chamber inclosing the carbon ends and amagnetic field arranged near the are for the purpose described and setforth.

3. In an electric-arc lamp, search-light, 850., the combination of apair of downwardlypointed parallel or converging carbons eontainingahigh percentage of metallic salts and a reflecting agent arranged abovethe luminous arc to prevent upward movement of air for the purposedescribed and set forth.

4. In an electric-arc lamp the combination of a pair ofdownwardly-pointed parallel or converging carbons containingahighpercentage of such metallic salts which give to the are a highilluminating power and a magnetic field arranged near the are for thepurpose described and set forth.

HUGO BREMER.

\Vitnesses:

CHARLES LE SnirLE, KARL SCHMITT.

